ﬁeld or at the hive may also provide useful information in this

respect).

Plot size: the area of each plot required will depend on a num-

ber of factors, e.g. the number and size of colonies, the crop type

and seasonal timing, but should be large enough to provide sufﬁ-

cient forage to ensure appropriate exposure of the test bees. In the

case of the standard attractive crops, at least 2500 m

for

Phacelia

and approximately 1 ha for rape and mustard are appropriate. This

should be considered in relation to the total number of bees (pro-

portion of the foraging population) exposed. In the case of

Phac-

elia

, plots may need to be irrigated to ensure that the crop remains

sufﬁciently attractive. Plots should be well separated to avoid bees

foraging on the wrong plot (2–3 km depending on local condi-

tions), but should be as homogeneous (e.g. microclimate, expo-

sure and surrounding landscape) as reasonably practicable. The

distance between plots should be recorded. The plots should not

be close to other ﬂowering crops or non-cultivated areas which

are signiﬁcantly attractive to bees. As a guide, the same separation

distance as for the test plots should be considered, taking into

account the size and attractiveness of the other crops or non-

cultivated areas. Bee-attractive weeds in the vicinity of the test

plots cannot be avoided, but it may be useful to record them dur-

ing the exposure phase when considered signiﬁcantly abundant.

Replicates: although very desirable, replication is often not fea-

sible because of the requirements for separation.

Number of colonies per treatment

⁄

plot: at least four colonies

per treatment (related to plot size and attractiveness of crop)

should be used. Additional colonies may be needed for speciﬁc

purposes, e.g. for pollen traps. No large apiaries should be present

in the area around the trial plots, and if bee colonies other than

those used in the study are present in the immediate vicinity, they

should be recorded.

2. Application of treatments

2.1 Test product(s)

Only formulated products should be used.

2.2 Toxic standard

⁄

reference product(s)

A toxic standard is usually not suitable for ﬁeld trials (e.g. due to

national restrictions on application of products harmful to bees),

but in speciﬁc cases a toxic standard known to present a high

hazard to bees may be used. In those cases where a toxic standard

is not included, it should be demonstrated otherwise that bees

have been exposed. Reference product(s) that present known haz-

ards to bees may also be included for comparison with the test

product.

2.3 Timing of application

Application timing should depend on the study objectives. Thus,

for a standard ﬁeld trial based on acute toxicity, the treatments

should be applied during the daytime when bees are demon-

strated to be actively foraging on the test crop. This may be

modiﬁed,

e.g.

when

testing

systemic

compounds

applied

pre-ﬂowering (seed dressings and soil-applied products) or for

assessing mitigation measures. Treatments should be applied in

as short a time period as technically feasible, ensuring that

conditions during application on the different plots are reasonably

similar. Ideally, there should not be any rainfall before the

treatments have dried, e.g. for about 2 h after application.

Shortly before application, the number of bees per m

, and

how the assessments are carried out, should be recorded. Where

a toxic standard has not been used, ideally a foraging density of

at least ﬁve bees per m

Phacelia

or two to three bees per m

on rape and mustard (for the crop areas given in section 1.5)

should be recorded shortly before application in order to verify

exposure. These ﬁgures should not be used as validity criteria on

their own. Lower ﬁgures should be explained and considered

with other evidence of exposure. When assessing exposure, it

should be remembered that foraging density may be affected by

the total area available, but at the colony level it will be deter-

mined by the total number of bees foraging on the test plots.

However, in other cases foraging levels need to be related to the

speciﬁc conditions of the trial, e.g. for less attractive crops and

pre-ﬂowering application of systemic compounds (where expo-

sure is related to a more sustained period that takes into account

the duration of ﬂowering).

2.4 Application rates

The product should normally be applied at the highest rate

recommended for the relevant ﬁeld use. Lower application rates

may be applied, e.g. if the off-crop risk needs to be assessed

(using drift rates of application) or when exposure on weeds in

orchards is tested (ground deposition rates). Volume of applica-

tion and nozzle type should be as recommended and should be

reported. Normally, a single application during ﬂowering will be

sufﬁcient, but multiple applications (according to the GAP) may

be appropriate in speciﬁc cases, e.g. for sprayed compounds that

have the potential to move to the ﬂowers via foliar uptake.

3. Mode of assessment and recording

3.1 Meteorological data

Temperature and humidity should be recorded at appropriate

intervals throughout the trial period either at the trial site or at the

nearest ofﬁcial weather station. Rainfall and sunshine or cloud

cover should also be reported.

3.2 Type, time and frequency of assessment

3.2.1 Type

The precise nature of the assessment regime used in

a particular ﬁeld trial will depend on its speciﬁc objectives. The

following parameters should always be assessed: ﬂight and

⁄

foraging activity in the crop as given by the number of bees per

(by monitoring a ﬁxed area, e.g. 1 m

, or using transects in

the crop, in both cases for a deﬁned period); general behaviour of

bees on the crop and around hives using a standardized approach;

mortality of bees (using dead-bee traps and possibly also on

water-permeable sheets placed in front of the hives and in the

crop); colony status

⁄

development (including consideration of dis-

ease and

Varroa

levels) at test initiation and test termination.

These should be regarded as the core endpoints, which are partic-

ularly relevant for the interpretation of all ﬁeld trial results.

318

Efﬁcacy evaluation of plant protection products

2010 OEPP/EPPO,

Bulletin OEPP/EPPO Bulletin

, 313–319